Rulings

If you control two Kamis of Whispered Hopes, the number of +1/+1 counters put on a permanent is two plus the original number. Three Kamis of Whispered Hopes add three, and so on.
If another permanent you control would enter the battlefield with a number of +1/+1 counters on it, it enters with that many plus one instead.
If two or more effects attempt to modify how many counters would be put onto a permanent you control, you choose the order to apply those effects, no matter who controls the sources of those effects.
The last ability is a mana ability. It doesn't use the stack and can't be responded to.
However, if Kami of Whispered Hopes somehow enters the battlefield with +1/+1 counters it, its first ability won't apply to itself.